To: Jeff Telander From: Dave Reeves

Project File Date: March 17, 2008

Re: Mineral Wool Production – Actual versus Allowable Emissions

Source 

Category Emission Point Format of Primary (MACT) Standard

Could 

Possibly

Calculate 

Allowable?

Info Needed to 

Calculate

Allowable 

Emissions

Mineral 

Wool

Cupolas

Emission Limits:

kg PM/ Mg melt

kg CO/ Mg melt

Yes Amount of melt

Curing Ovens Emission Limit:

kg formaldehyde/Mg melt Yes Amount of melt

We reviewed all of the reported emissions data in NEI and TRI, as well as the emission limits 

in the Mineral Wool Production MACT standard and state operating permits. In general, all 

of the emission limits are based on production levels (e.g., mass of pollutant allowed to be 

emitted per mass of material melted). Even though production levels could be increased at 

most of the currently operating facilities, there are equipment and process limitations on how 

the melting furnaces (cupolas) are operated – which limits the potential (allowable) emissions 

for a given facility. Market forces also impose production caps on existing facilities and 

probably account for much of their current excess capacity. The cupolas are considered 

batch operations, but are run on a continuous or semi-continuous basis to save time and 

energy to heat up the furnace for each batch. Because melting operations are the production 

limiting process at these manufacturing facilities, the reported emissions are representative of 

the current market and are believed to at the highest level (since the overall mineral wool 

market is declining). 

We also reviewed data from the North American Insulation Manufacturers Association 

(NAIMA) in response to a request for summary MACT compliance test data for mineral 

wool production facilities. Six facilities reported cupola particulate matter (PM) emissions

and three facilities operating bonded lines reported formaldehyde emissions from curing 

ovens – see attached summary table.

The arithmetic average PM emission rate for all cupola PM emissions data is 0.044 pounds 

PM/ton melt. (We also calculated individual facility averages and means and came up with 

basically the same value.) The average formaldehyde emission rate for all curing oven 

formaldehyde emissions data is 0.038 pounds formaldehyde/ton melt. Allowable PM and 

formaldehyde emission rates under the Mineral Wool MACT standard are 0.1 pounds 

PM/ton melt and 0.06 pounds/ton melt, respectively. The allowable PM emission rate is 

approximately 2.3 times higher than the average of the reported PM emission rates

(0.1/0.044). The allowable formaldehyde emission rate is approximately 1.6 times higher 

than the average of the reported formaldehyde emission rates (0.06/0.038). 

Based on these reported emission rates and the equipment and process limitations, we are 

recommending that allowable emissions be estimated to be 2 times the actual emissions for 

each facility for purposes of the risk modeling. We believe that a 2X factor applied to the 

most recent reported emissions is realistic and does not grossly overstate potential emissions.
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A B C

Facility

Cupola Emissions (lb 

PM/ton melt)

Curing Oven Emissions (lb 

formaldehyde/ton melt)

Amerrock Products LP (Nolanville Plant) - Cupola No. 1 0.076

Amerrock Products LP (Nolanville Plant) - Cupola No. 2 0.096

Industrial Insultion Group, LLC (formerly Owens Corning) - Cupola Furnace Outlet 0.08

Industrial Insultion Group, LLC (formerly Owens Corning) - Curing Oven 0.059

Isolatek International - Cupola Baghouse 0.008583

Isolatek International - Cupola Baghouse 0.047476

Isolatek International - Cupola Baghouse 0.007352

Rock Wool Manufacturing (Leeds, AL) - No. 1 Cupola 0.055

Rock Wool Manufacturing (Leeds, AL) - Curing Oven 0.017

Sloss Industries Corp. - Cupola Baghouse 0.049

Thermafiber, Inc. (Wabash, IN) - Cupola No. 2 Baghouse Outlet 0.00901

Thermafiber, Inc. (Wabash, IN) - Cupola No. 4 Baghouse Outlet 0.00788

Thermafiber, Inc. (Wabash, IN) - Bonded Curing Oven RTO Outlet 0.037

AVERAGE = 0.044 0.038